Sleeve for grounding bushing-mounted contact to plate

ABSTRACT

In an electrical interconnection assembly of the type which comprises a conductive plate having elongated contacts mounted in respective apertures thereof by means of respective thermoplastic insulating bushings, a removable sleeve is provided for grounding any contact to said plate without damaging the plate, the bushing, or the contact. The sleeve comprises a cylindrical member having a sharpened lead-in edge at a first end, a fluted body portion, and at the other end, a plurality of arcuate fingers shaped to grip said contact when said sleeve is inserted thereover. To ground any contact, the sleeve is slipped over the contact, first end downward, and the lead-in portion is driven between the plate and bushing such that the fluted body portion makes a good connection with the plate and the gripping fingers make a good connection with the contact.

United States Patent 11 1 Siegler 1451 Nov. 20, 1973 SLEEVE FOR GROUNDING BUSHING-MOUNTED CONTACT TO PLATE [75] Inventor: Frederick J. Siegler, Santa Monica,

Calif.

[73] Assignee: Elco Corporation, Willow Grove, 7 Pa.

[22] Filed: May 10, 1972 21 Appl. No.: 252,074

[52] US. Cl. 339/14 R, 339/95 R [58] Field of Search 339/14 R, 14 L, 14 P, 339/14 R, 14 T, 176 R, 176 L, 176 M, 17.6

MF,176 MP, 176?, 221 R, 221 L, 221M,

95 R; l51/4l.73; 85/36; 248/43, 56;

285/158; 287/5204, 52.06, 53 SS; 24/81 PE,

[56] References Cited UNITED STATES PATENTS 1,832,940 11/1931 Matthes 24 1223 1,204,625 11/1916 Wheelock 3,214,200 10/1965 Carlson et al.... 3,231,843 1/1966 Anteset al 339 14 R 8/1967 Creedon 339 14 R 1/1971 Crimmins 339/14 R Primary Examiner-Marvin A. Champion Assistant Examiner-Robert A. Hafer Attorney-D. R. Pressman [57] ABSTRACT In an electrical interconnection assembly of the type which comprises a conductive plate having elongated contacts mounted in respective apertures thereof by means of respective'thermoplastic insulating bushings, a removable sleeve is provided for grounding any contact to said plate without damaging the plate, the bushing, or the contact. The sleeve comprises a cylindrical member having a sharpened lead-in edge at a first end, a fluted body portion, and at the other end,

' a plurality of arcuate fingers shaped to grip said contact when said sleeve is inserted thereover. To ground I any contact, the sleeve is slipped over the contact,

first end downward, and the lead in portion is driven between the plate and bushing such that the fluted ,body portion makes a good connection with the plate and the gripping fingers make a good connection with the contact.

10 Claims, 3 Drawing Figures I SLEEVE FOR GROUNDING BUSHINGJVIOUNTED CONTACT'TOPLATE BACKGROUND: FIELD OF INVENTION This invention relates to the electrical connector art, andparticularly to an electrical interconnection assembly of the type comprising a conductivelplate having cardedge connectors mounted thereon'by means of insulating hubs which extend through holes in the plate,

with the tailsor secondary mating portions of the contactsextending out from the hubs on the underside of the plateso thatsuch tails can be interconnected by wire wrapping meansfThe present invention comprises aground sleeve which can be applied over any contact tail and between the insulating bushing and the sides of thehole in the plate in order to groundsuch contact to the plate"withoutdamaging the contact, the insulating bushing, or the plate, and which can be readily be removed, if desired.

BAC KGROUND: DESCRIPTION OF PRIOR ART In complex electrical systems, such ascomputers or other data processing equipment; it is common practice to employ a plurality of printed circuit boards, each of which contains electrical circuitry designed to accomplish a specific sub function within the entire system. Connections to these boards or car'ds-areprovided by "means of cardedge connectors into which the cards can be plugged. The cardedge connectorsmust, of course, in turn be interconnected andconnectedto other equipment.

One way in which cardedge connectors are commonly. interconnected is bymounting the cardedge connectors on a metal plate such that the tails or secendary mating portionsof the contacts of the cardedge connectors protrude from the lower surface of the plate.

The cardedge connectors themselves consist of insulated housings having'cylindrical hubson their lower surface,.which hubs are mounted in apertures of the metal plate by forcefit,with the contact tails being in turn mounted in the hubs, also by force fit, such that nector was removed and a metal bushing was substi-' tuted which served both to mount the contact in the plate and connect the contact electrically to the plate.

' v This method did not allow much flexibility since once the insulating bushing was removed and a metal bushing was substituted, the ground connection became permanent and it would not be possible to insulate that contact from the plate again. In addition, it was expensive to perform all the steps necessary to effect this operation. Furthermore, once a cardedge connector was installed to the plate, and wiring beneath the plate was impossible to ground the contact to'the plate through the use of a metal bushing of the aforedescribed type.

completed, it would be very difficult, if not practically Another method of connectinga contact to the plate electrically'was through the u'se of a wire wrapped connection. However, such a connection required the use of an intervening wire between the contact and the plate, and,as will be recognized-by those skilled in the art, this is electrically undesirable since such a wire may have high resistance and may pick up spurious noise signals.

Accordingly, several objects of the present invention are (l) to provide aneconomical', reliable, and simple means for grounding a contact to a supporting plate, (2) to provide meansfor grounding a contact to a plate which can be removed and replacedat will and which can be applied to any selected contact within a large array of contacts, and (3) to provide amethodof grounding a contact to a plate which is mechanically and electrically secure and reliable. Other objects and advantageswill become apparent from a consideration of the ensuing description.

DRAWINGS FIG. l is a partial bottom axonometeric view ofa plate having a cardedgeconnector mounted thereon,

including a showing of several ground sleeves according to the invention. FIG. 2 is a sectional view taken along the line22 of FIG. 1. FIG. 3 is anaxonometeric cutaway view of the ground sleeve according to the invention.

DESCRIPTION of square or rectangular cross-section which protrude from the lower surface of plate 110. Connections between'different cardedge connectors are effected by means of wire wrapped interconnections between tail portions 18. Lastly, the contacts have mounting or body" portions (not shown) which join secondary mating portions 18 with primary mating portions; such body portions aid in mounting the contacts in connectorl2. A connector 12 is mounted on plate 10 by means of insulating hubs, such as 20, which extend from the lower surface of connector 12 and are remined in respective apertures of plate 10 by force fit, with contact tails 18 being in turn held in the respective hubs, also by force fit. The insulator of connector 12,

of which hubs 20 may be an integral part, is made of thermoplastic material, such as nylon or polycarbonate which, as is well known, is slightly compressible.

According to the invention, any contact tail 18 may be connected to plate 10 electrically in a reliable, economical, and simple manner by the use of the ground sleeve of FIG. 3. One ground sleeve is shown partially installed in FIG.1 at 22 and another is shown fully installed at 24. The ground sleeve comprises a generally cylindrical member, one end of which has a sharpened or tapered lead-in end 26 (FIG. 3) and the other end of which has a reducing portion 28 which provides an internal shoulder 30 facing lead-in end 26 and an external shoulder 36. Connected to reducing portion28 and extending from shoulder 36 are four integral fingers, such as 32, each of which has an arcuate cross section. The fingers extend from an end of reducing portion 28 of the sleeve toward an imaginary extension of a central axis (not shown) of the sleeve.

The outer surface of the portion of the sleeve between the reducing and lead-in portions is fluted as indicated at 34 to provide a plurality of edges to aid in making a low resistance connection with the walls of the aperture of plate 10.

The entire sleeve is preferably made of springy material, such as heat-treated beryllium copper. In one example where tail sections 18 of the contacts in connector 12 had a square cross section and measured 25 mils on each side, the sleeve was about Veinch high, with its other dimensions scaled proportionately as indicated in FIG. 3. The entire sleeve can be formed by machining and other well known metal-working techniques from an integral cylindrical blank.

OPERATION In order to ground any contact tail 18 to plate 10, an insulating sleeve according to the invention is fitted over a contact tail as indicated at 22 (FIG. 1). When the sleeve is thusly installed over a tail, the tail will spread gripping fingers 32 (FIG. 3), whereby these fingers will exert a strong gripping force against the four sides of tail 18. However, since there are as many gripping fingers 32 as sides of tail 18 (four), these fingers will not engage or damage the corners of tails 18, thus advantageously leaving such corners sharp, as required for effective wire wrapping operations.

With the aid of a simple, cylindrical installation tool (not shown) designed to engage the upwardly-facing shoulder 36 (FIG. 3) of the sleeve, the sleeve is forced downward until its sharp lead-in edge 26 fits between the edge of bushing 20 of card-edge connector 12 and the side of the aperature in the plate. With plate 10 and connector 12 well supported and using an arbor press or a hammer, the sleeve is pushed between the bushing 20 and the side of the hole until shoulder 30 of the sleeve meets the end of the bushing as indicated at 38 (FIG. 2). The sleeve is now fully installed.

An excellent connection is now provided between the contact tail and the plate since the spring fingers of the sleeve grip the contact tail firmly and since the fluted outer surface 34 of the sleeve engages the sides of the hole of plate 10.

If necessary, the sleeve can easily be removed with the aid ofa pliers having a knife-edge cylindrical grasping jaw. The pliers'are used to grasp the extending fluted portion 40 (FIGS. 1 and 2) of the sleeve,

' whereby the sleeve can be pulled upwardly to be removed. After such removal, thermoplastic hub 20 of connector 12 will spring back to its normal shape and still retain its contact firmly.

It is thus seen that an extremely simple, yet highly reliable and versatile means for grounding any contact tail to a plate is provided according to the invention.

It will be recognized that gripping fingers 32 can be spaced in a non-symmetrical fashion, rather than as indicated, in order to engage the sides of a non-square rectangular contact tail, if desired.

While the above description contains many specificities, these should not be construed as limitations upon the scope of the invention but merely as an exemplification of one preferred embodiment thereof. The

true scope of the invention is indicated by the subject matter of the appended claims and their legal equivalents.

I claim:

1. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising metal sleeve means for selectively connecting any of said members to said plate, said sleeve means, comprising a cylindrical conductive member having a central longitudinal axis, having one end tapered to sharp lead-in edge means for fitting between said bushing and the side of said hole, and finger means at the other end of said conductive member for gripping said member when said sleeve means is inserted thereover, said finger which coverage towards said central axis means including a plurality of resilient fingers.

2. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising a sleeve for selectively connnecting any member to said plate, said sleeve comprising a cylindrical conductive member, one end of which is tapered to a sharp lead-in edge which is dimensioned to fit between said bushing and the side of said hole, the other end of which comprises a plurality of fingers dimensioned to grip said member when said sleeve is inserted thereover, said sleeve having a body which is straight along any longitudinal path thereon, and a cylindrical cross section, said outer surface being fluted to aid in making a good electrical connection with the sides of said hole.

3. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising a sleeve for selectively connecting any member to said plate, said sleeve comprising a cylindrical conductive member, one end of which is tapered to a sharp lead-in edge which is dimensioned to fit between said bushing and the side of said hole, the other end of which comprises a plurality of fingers dimensioned to grip said member when said sleeve is inserted thereover, said sleeve including a shoulder surface on the inside of said sleeve adjacent said other end thereof and facing said one end thereof for limiting travel of 1 said sleeve when it meets said bushing after said sleeve is inserted between said bushing and said side of said hole.

4. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising a sleeve for selectively connecting any member to said plate, said sleeve comprising a cylindrical conductive member, one end of which is tapered to a sharp lead-in edge which is dimensioned to fit between said bushing and the side of said hole, the other end of which comprises a plurality of fingers dimensioned to grip said member when said sleeve is inserted thereover, said fingers extend outward from the end of said sleeve toward an imaginary center axial extension of said sleeve.

5. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising a sleeve for selectively connecting any member to said plate, said sleeve comprising a cylindrical conductive member, one end of which is tapered to a sharp lead-in edge which is dimensioned to fit between said bushing and the side of said hole, the other end of which comprises a plurality of fingers dimensioned to grip said member when said sleeve is inserted thereover, said sleeve having a body portion between said two ends thereof which has a cylindrical cross section of uniform diameter, a reducing portion adjoining the end of said body portion remote from said one end of said sleeve which narrows the diameter of said sleeve, said fingers adjoining a surface of said reducing portion adjacent the axis of said sleeve.

6. The invention of claim 5 wherein said reducing portion has an inner surface which forms a shoulder facing said one end of said sleeve, thereby to limit travel of said sleeve when said shoulder meets said bushing after said sleeve is inserted between said bushing and the side of said hole.

7. The invention of claim 6 wherein said fingers extend outwardly from said sleeve toward an imaginary central extension of said sleeve, said fingers are four in number, and each has an arcuate cross section.

8. The sleeve is claim 5 wherein said fingers extend outwardly from the end of said sleeve toward an imaginary central axial extension of said. sleeve.

9. The sleeve of claim 8 wherein said fingers are four in number, so as to grip effectively an elongated member with a rectangular cross section, and wherein each finger has an arcuate cross section.

10. The sleeve of claim 6 wherein said fingers are four in number, each having a curved cross section. 

1. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said Elongated members and the sides of said holes, the improvement comprising metal sleeve means for selectively connecting any of said members to said plate, said sleeve means, comprising a cylindrical conductive member having a central longitudinal axis, having one end tapered to sharp lead-in edge means for fitting between said bushing and the side of said hole, and finger means at the other end of said conductive member for gripping said member when said sleeve means is inserted thereover, said finger which coverage towards said central axis means including a plurality of resilient fingers.
 2. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising a sleeve for selectively connnecting any member to said plate, said sleeve comprising a cylindrical conductive member, one end of which is tapered to a sharp lead-in edge which is dimensioned to fit between said bushing and the side of said hole, the other end of which comprises a plurality of fingers dimensioned to grip said member when said sleeve is inserted thereover, said sleeve having a body which is straight along any longitudinal path thereon, and a cylindrical cross section, said outer surface being fluted to aid in making a good electrical connection with the sides of said hole.
 3. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising a sleeve for selectively connecting any member to said plate, said sleeve comprising a cylindrical conductive member, one end of which is tapered to a sharp lead-in edge which is dimensioned to fit between said bushing and the side of said hole, the other end of which comprises a plurality of fingers dimensioned to grip said member when said sleeve is inserted thereover, said sleeve including a shoulder surface on the inside of said sleeve adjacent said other end thereof and facing said one end thereof for limiting travel of said sleeve when it meets said bushing after said sleeve is inserted between said bushing and said side of said hole.
 4. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising a sleeve for selectively connecting any member to said plate, said sleeve comprising a cylindrical conductive member, one end of which is tapered to a sharp lead-in edge which is dimensioned to fit between said bushing and the side of said hole, the other end of which comprises a plurality of fingers dimensioned to grip said member when said sleeve is inserted thereover, said fingers extend outward from the end of said sleeve toward an imaginary center axial extension of said sleeve.
 5. For use with an electrical interconnection assembly of the type which comprises a perforated plate having conductive portions at least at the holes thereof, with electrically conductive elongated members mounted in said holes by means of compressible insulating bushings which are force-fit between said elongated members and the sides of said holes, the improvement comprising a sleeve for selectively connecting any member to said plate, said sleeve comprising a cylindrical conductive member, one end of which is tapered to a sharp lead-in edge which is diMensioned to fit between said bushing and the side of said hole, the other end of which comprises a plurality of fingers dimensioned to grip said member when said sleeve is inserted thereover, said sleeve having a body portion between said two ends thereof which has a cylindrical cross section of uniform diameter, a reducing portion adjoining the end of said body portion remote from said one end of said sleeve which narrows the diameter of said sleeve, said fingers adjoining a surface of said reducing portion adjacent the axis of said sleeve.
 6. The invention of claim 5 wherein said reducing portion has an inner surface which forms a shoulder facing said one end of said sleeve, thereby to limit travel of said sleeve when said shoulder meets said bushing after said sleeve is inserted between said bushing and the side of said hole.
 7. The invention of claim 6 wherein said fingers extend outwardly from said sleeve toward an imaginary central extension of said sleeve, said fingers are four in number, and each has an arcuate cross section.
 8. The sleeve is claim 5 wherein said fingers extend outwardly from the end of said sleeve toward an imaginary central axial extension of said sleeve.
 9. The sleeve of claim 8 wherein said fingers are four in number, so as to grip effectively an elongated member with a rectangular cross section, and wherein each finger has an arcuate cross section.
 10. The sleeve of claim 6 wherein said fingers are four in number, each having a curved cross section. 